MAR-218: Improve linter reporting in the test runner script:

- Show info messages on what linter is currently running, and
explicitly report success and failure.

MAR-218: Fix incorrect logic for switching directory:

- No piping can be used (since that would be a subshell and would not
affect the working directory for the remainder of the script run).

MAR-218: Fix the test run logic in test runner script:

- Linter tests should _always_ be run.
- Test report files should be appended to when using tee.
- Get rid of excess molecule destroy (probably not required any
longer). This will reduce the output and speed up things a little
bit.

MAR-218: Fix some minor issues for the test runner script:

- No need to use the $ variable syntax for arithmetic operations.
- Use correct form when printing the list of roles (@ -> *).
- Fix missing quote when assembling the list of roles.

MAR-218: Reimplement linting supports in test runner scrupt:

- Molecule no longer has command for running the linters, so a small
wrapper around linters has to be implemented.

MAR-128: Updated script for running tests and documentation:

- Updated script, removing parts related to separate platform testing
from old version of Molecule.
- Updated instructions for running the test script.

MAR-110: Implemented script for running tests for all roles:

- Updated gitignore file to ignore test reports.
- Updated instructions for running tests.
- Added Bash script that wraps around Molecule and allows output of reports into
a directory.